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How Search Engines Work: Crawling, Indexing, and Ranking

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07 Jan 2021


Search engines organize the internet's content in such a way that searchers can find results relevant to the information they are seeking. For your content to appear in the users' search results, your content has to be visible to search engines.

How Do Search Engines Work?

Search engines primarily perform three functions:

• Crawling; Search for any new and updated internet content.

• Index. Store and organize the content found during the crawling process. Once your page appears in the index, it can be displayed in the search results to users' queries.

• Rank. Provide content that is most relevant to what the searcher is looking for. This means that pieces of internet content are arranged from the most relevant to the least.


Crawling is a process through which search engines send out robots, known as crawlers to find new and updated content on the internet; could be PDF, webpage, an image, just to mention a few. Crawlers use links to discover content. They start by fetching a few web pages and then use the links of those webpages to find new URLs. Through this, crawlers can identify new and updated internet content. They then add their identified content to their index which is known as caffeine. Caffeine is a huge database of discovered URLs that are to be retrieved when users conduct a search related to the content.


What is the search engine index? An index is a massive database that stores content discovered by crawlers. So, when search engines find information, they process it and then stores it in the index to be used later when an internet user searches for a piece of content that matches it.

Search Engine Ranking

When someone searches for some information via google, for instance, search engines scour their index to identify content that has more relevant information to what the searcher is seeking. It then orders the identified content with the hopes of solving the researchers’ problem. This process is called ranking. Generally, the higher your website is ranked, the more search engines believe your site is relevant to the query.

By the way, did you know you can block search engines from crawling some parts of your website or instruct them to avoid keeping certain pages in their index? Yes, it is possible. Although there a bunch of reasons you may want to keep search engines away from your site, your content can only be found by searchers if it is accessible to crawlers and that it is indexable.

Can Search Engines Find Your Pages?

As mentioned above, making sure your content can be crawled and indexed is key to allowing your content to show up in search results. If you have a website running, see how many of your pages are indexed by search engines.

The number of results you will get from google is not exact but, it tells the number of pages from your site that are indexed by search engines and how they are showing up in the search results.

You can have access to more accurate results if you sign up for free at google search console, that is, if you don't have an account yet. This tool allows you to submit your site maps and monitor how many of your pages are stored in the search engines index.

If you are not finding your pages in the search results, the following could be possible reasons:

• Your site is brand new and hasn’t been crawled yet.

• Your site is not linked to any other website other than yours.

• Your site has been reported for spammy tactics.

• Your site contains crawler directives a basic code that blocks search engines from crawling parts of your site.

Use Robot.Txt. To Direct Google Away from Certain Sections of Your Site

Most people think about ensuring google can find their important pages, but fail to recognize that you never want google to come across. They could be old URLs that have low content, or maybe duplicate URLs. Use robot.txt to direct google away from such sections of your website.

Robot.txt files suggest to search engine crawlers, which parts of your website it should and shouldn't crawl. They also direct the speed at which search engines crawl your website.

How Do Googlebot Treat Robo.Txt Files?

• Suppose Googlebot can't locate robot.txt on your website, it will proceed and crawl your site.

• If Googlebot finds a robot.txt file for your site, it will abide by the suggestions and proceed to crawl your site.

• If Googlebot encounters any error in an attempt to locate a robot.txt file for your site and cants determine if it exists or not, it will not crawl your site.

However, keep in mind there are people with bad intentions who certainly don't follow this protocol. Some of these people tend to use a robot.txt file to find where you have located your private content. While you may use this as a reason to block search engines from accessing some parts of your site, locating such URLs in publicly accessible robot.txt file does more harm than good. Instead, NoIndex such important pages and gate them behind a login form.

How Can Googlebot Find Your Important Content?

It is important to ensure that search engines can find all the important content you want to be indexed. Can crawlers access your website? Is your content hidden behind login forms? For some reason, you may require users to log in first before accessing some piece of content from your website. In such cases, search engine crawlers can't access such pages.


Search engines perform the functions crawling, indexing, and ranking to display the most relevant content in google search results. So, ensuring your content is SEO optimized is crucial if you want it to appear in the users' search results. Be very careful when using some the tolls such robot.txt file which, can put your private content at risk of being accessed by unauthorized people. Above all, the quality of your content matters if you want search engines to rank it.

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